In some environments, such as indoor or in areas where many natural or manufactured obstacles are present, for example, GNSS signal reception may be weak. In these environments, beacon positioning systems that rely entirely on GNSS signals are generally inoperable. Thus, other types of beacon location systems that rely on received signal strength or signal timing, for example, may be used.
Received signal strength is often used to estimate range of a radio beacon from multiple receivers, which may in turn be used to estimate the radio beacon's location. When obstacles are present between the radio beacon and the receivers, the radio beacon signals may be blocked or reflections may result such that a determined location is less reliable and less accurate. In addition, for receivers with directional antennas, correct determination of the radio beacon's location is dependent on an orientation of the receivers relative to one another. Orientation is typically performed manually because automated methods are often not reliable. For example, determining orientation using magnetic field sensors of the beacons is particularly unreliable in environments in which metal objects are present.
In some environments, signal timing may produce more accurate range results than received signal strength, however, signal timing is not usable with third party hardware because timing synchronization between the beacon and the receiver is not achievable. As a result, applications of signal timing based location determination may be limited.